Well apparatus



July 8, 1941. E. l.. CRAWFORD 2,248,150

WELL APPARATUS Filed Aug.v 12,'1938 o o l 5 s i 14 11 18 6 l 1.5' ,J4 20 22 17 19 16 -JHJJV'QI-u' zg 20 21 s1 IZ 24 13 f 2z 11 25 i 1o l I l l f. 16 14 INVENTOR.

2' Earl L. Crawford BY www ATTORNEY. y

diiilculties Vingfluid between the movement lof the sleeve relative to the drill Patented July s, 1941 UNITED sTATi-:s PATENT QFFICE Earl L. Crawford, Whittier, Calif. .Application August l2, 1:9318, Serial No. 224,5614 s claims. (ci. isc-1s) This invention relates to rotary well drilling apparatus and in particular, contemplates devices adapted for assembly in a string of drill pipe .to resiliently center and guide the pipe string in the Wellshaft and thereby obviate the tendency .of a long string of pipe to bend and spiral in the hole, whic with conventional apparatus, often results in tilting of the bitand the formation of a crooked hole.` Numerous other are encountered in rotary well drilling, `as a consequence of the drag of the pipe string on the wall of the hole incident to the bending of the pipe,

art.

A principal object is to provide a drill stem which includes a plurality of tubular sections arranged in spaced relation in the length of the string, each section carrying laterally expansible means to bear against ,the wall of the hole to center and guide the string in the casing and the hole, and particularly maintain the bit in a substantially vertical position. f

Another object is the provision of a sleeve through which the drill stem may rotatably extend carrying the upper and lower ends of spiral bowed spring shoesslidably in retaining slots,'

whereby the shoes adapted to bear against the formation may individually compensate for projections and cavities in the well shaft by the varying degree of their respective lateral extension, while the spiral arrangement of the springs with respect .to the axis of the drill stem will facilitate the sleeve in following the bit as the hole is deepened.

Another object is to provide in a device of the character above-indicated, a tubular member having threaded connections for assembly'in a drill pipe string carrying bearings for the independent rotatable support of a sleeve, there being apassage formed between the member and sleeve for the upward iiow of mud drilling fluid discharged from the bit secured to the lower end of the drill string for cooling and the lubrication of the bearings.

Another object is to provide a series of openings inthe rotatableshoe-earrying sleeves to ob- Vviate the accumulation of abrasive particles of the drillings carried by mud circulating uid within the sleeve and around the bearings to minimize -wear 'of the bearings and the races in which they are carried, as well as to avoid settling of other constituents of the mud circulatdrill stem and sleeve which vwould otherwise tend to restrict free rotative which are well known to the filiv string. sleeve 9 Still another object is to provide a bell-shaped shield mounted on the drill stem to overhang each of the drill stem-centering units to deect cavings and prevent the accumulation of viscid greater than the curve of the wall'of the hole in which the unit is to be located. y

Other objects and corresponding advantages as, for example, a greater simplicity of construc- 'tion and operation, durability, ease of assembly and replacement of worn parts, as well as -positive action, will be apparent to those of skill in the art from an examination of the following description read in the light; of the accompany ing drawing, in which: I

Fig. 1 is an elevation of one unit of my invention illustrated as assembled in the drill stem to center and guide the bit;

Fig. 2 is a sectional view of the device taken at right angles to the view of Fig. 1 with the spring shoes partially broken away;

Figs. 3 and 4 are sectional views taken on correspondin'gly numbered lines of Fig. 1.

Referring to the drawing in detail, the numerals of which indicate similar'parts throughout the several views, 5 designates generallya hollow drill pipe section to the lower end of which is threaded a tubular member 6 of the centering unit of my invention. It will be understood that the drill stem is made up of a plurality of stands of drill sections 5 having a series of centering units comprising tubular,A members 6 threaded at spaced intervals in the string to center and guide the entire drill stem in the well shaft. A fish tail bit 1 of cnventional construction is shown in Fig. l. as attached to the lower end of tubular member 6. Each centering unit comprises, as above noted, a tubular member .6, and communicates through its bore the pipe sections 5 above and below 1t through which mud driuing uuid 'thereof for a purpose later referred to. The is held concentric with the member by v of the tubular member 9 are diametrically enlarged as at Il within the heads and are formed with a pair of peripheral grooves I which comprise races for ball bearings I6. The bearings I6 extend laterally of the member and move in complementary grooves I1 formed in the wall of each head. Bearings I8 are inserted through .threaded openings Il which register with the respective grooves |1 in each head. The openings |9 are normally closed by screws I9, the heads 29 of which lie iiushwith the peripheral v surface of the respective heads Il.

l A series of rectangular recesses 2| are formed in the periphery of each head at a slight angle to the axis of the drill stem, i. e., slanting in a counterclockwise direction from top to bottom. A second narrower recess 22 extends from each recess 2| through the adjacent ends of the respective heads I I. Bowed spring steel springs or shoes 23 are carried rotatably with respect to the drill stem by the sleeve to resiliently bear against the formation or casing through which the drill stem extends. The shoes 23 are curved in cross section to any desired degree, but preferably are carried to a degree equal to or greater than the curve of the wall of the hole being drilled. Shoes 23 are spiralled around sleeve 9 for a purpose later referred to. 'I'he ends of the vshoes extend into respective recesses 2| and are enlarged, at at 24, to prevent withdrawal through recess 22. A collar 25 encircles each head Il and is welded or otherwise secured in a position over the ends of the shoes 23. A series of equi-spaced downwardly diverging ports 2t are formed in the lower head II, and extend from a point within the sleeve above the bearings I8 therein outwardly through the head below the collar 25 to communicate the bore of the head and the well shaft, and thereby permit gritty constituents of the mud and drillings to gravitate'away from the bearings.

Abrasive particles carried by the lubricating fluidv may also flow from the sleeve through slots I0.

A' bell-shaped shield 21 encircles the tubular member I above the upper bearings being attached to said member by welding or the like. The shield 21 flares outwardly to a diameter greater than the outside diameter of the upper head I I which it overhangs, but terminates above the upper edge of the upper head to permit the flow of circulating fluid through the sleeve 9, as above referred to.

In operation the centering unit of my invention is threaded into the string of drill pipe as the pipe is assembled and lowered inthe hole as above noted.' Due to the inherent tendency of the shoes 23 to bow outwardly, they will each individually bear against the casing or, where positioned below the casing, against the wall of the hole above the bit 1. as shown in Fig. l. Due to the great weight of the drill string, the latter will tend to bend in the hole and as the string is rotated incident to drilling, will, if its tendency to bend is not. restrained, drag on the wall of'the hole, dislodging debris and preventing emcient mudding up of the hole by the circulating yfluid and, will further result in tilting the lower end' of the pipe and the bit which will be conducive to the formation of a crooked hole. It will be observed that the outward expansion of the spring shoes 23 of the respective centering umts of my invention against the casing and hole will reduce to a minimum these results by retaining the drill pipe substantially in-the center of the hole in a vertical position. I'he pressure exerted by shoes 23 against the wall of the hole will be substan- `tially equal regardless of the contour of the forcompensated for by-the further lateral extension of the individual shoes moving across the cavity.

K The-sleeve 9 and shoes 23 may, of course, remain nonrotatable as the drill stem and bit are rotated. 'Ihe spiral arrangement of the shoes on the sleeve 9 facilitates lowering of the units in the well with the drill stem as the shoes will tend to rotate the sleeve slowly as the drillpipe is lowered, and thereby avoid riding directly over jutting obstructions in the vhole which might otherwise tend to resist their downward `movement. By reason of the cross-sectional curve of the individual shoes, the latter will not cut into the wall of the hole.

Circulating mud iluid introduced into the drill stem` at the well surface will discharge from the orifices of the bit 1 to cool the same and will thence flow upwardly toward the well surface in the usual manner. A portion of the fluid discharged from the bit will flow through the sleeve 9 to cool and lubricate the bearings I9. Abrasive particles tending to pack in the lower endof the sleeve will gravitate through ports 2B.

Occasionally cavings and accretions of drillings. particularly from sticky shale and clay formations, accumulate around the drill pipe over'collars and the like and not only obstruct eillcient operation of the drill pipe and impede circulation, but also make diillcult the removal of .the pipe from the well. In the present invention the flare of the shield 21 will enlarge the hole through the pipe-encircling accumulations whereby they will more easily pass over the head and bowed shoes to the bottom of the hole where they may be thoroughly disintegrated by the bit and removed from the well by circulating fluid.

Restriction in the well shaft will occasionally tend to obstruct the running of a pipe carrying the bowed springs of my invention into and out of the hole. However, byreason of the fact that each shoe is retained within the recesses of respective heads by the enlargement on the ends of the shoes, the lower head will pull the shoes through such a restriction if the latter is met as the string is being lowered in the well, and the upper head will similarly pull the shoes through a restriction formed as by cavings encountered as the string is being pulled from the well, thereby obviating the tendency of the spring shoes to pile up or buckle, which is a result common in', conventional devices which operate to y push the bowed shoes through the well'shaft.

It will thus be seen that I have provided an eillcient drill pipe centering and guiding device,

. wall of the casing, the shoes of which operate independently to exert a substantially'equal pressure against the sides of the 'hole so as to resiliently resist bending, tilting, and other distortion of the pipe.

While I have described but one embodiment of Y my invention, it will be understood that numerous changes in size, design, shape, number and proportion of the various 'carts may be made, and that any features may-be adopted in similar apparatus for centering and guiding sucker rod or tubing strings in a casing or in an open hole,

without departing from the spirit of my invention .as defined by the appended claims.

What I claim and desire to secure by Letters Patent is:

.1. In a device of the character described, a drill stem, a sleeve rotatably encircling said drill stem, said sleeve being ofgreatery inside diameter than the outside diameter of said drill stem to form a circulation passage through s aid'sleeve around said stem, a plurality of bowed spring shoes having their ends slidably attached to said sleeve.

2. In' a device of the character described, a drill stem, a sleeve encircling said stem, bearings between said sleeve and said stem, there being a passage formed between said sleeve and stem for admission of fluid from the well to lubricate said bearings, said sleeve having lateral openings and movable through the hole with said stem, said shield being ared laterally and downwardly to the diameter greater than the diameter of the upper end of said sleeve to enlarge the opening through debris accumulated in the well above the sleeve to facilitate withdrawal of said stem from the hole through the debris. t

4. In a device of the character described, a drill stem, a pluralityoi shoes, means on said stem to receive the lower end of each shoe, said shoes being longitudinally slidable relative. to said stem, means rigidly attached to said stem to limit the upward sliding movement ot said lower attached end of each shoe relative to said stem as the stem is lowered in the well to pull the shoes through the well shaft.

5. In a device of the character described, a

' tubular member, a plurality of ,outwardly bowed springs, means to slidably connect the ends of therein above said bearings for removal of abrasive particles in the fluid.

3. In-a device of the character described, a drill stem carrying a bit at its lower end, a sleeve encircling said stem carrying a series of shoes to engage the wall of the hole through which the stem is lowered,.and an annular shield encircling the stem and secured thereto above said sleeve each of saidl springs independently of one another to said tubular member, and meansrigidly attached to said tubular member to limit the slid'- ing,movement of said springs relative to said tubular member.

6. In a device for centering a drill pipe string in a well hole, a series of bowed spring shoes, a'

pair of sleeves connected by said string in spaced relationship, each -of said sleeves having a recess therein to slidably receive the ends o! said shoes, and means connected to said lowermost sleeve to limit the upward movement of the lower end of said shoes while the string is being lowered in the well, the upper end of said shoes being movable upwardly in the recess of said upper sleeve while the lower ends of said shoes are engaged by said last-named means.

EARL L. CRAWFORD. 

